The present invention relates to a restraining apparatus applicable to animal experiments, and more particularly, to an animal restraining apparatus and animal restraining procedure for using the same, such that the animal can be monitored continuously in a conscious state for more than seventy two hours without giving any anesthesia, tranquilizer, or muscle relaxation agent, and, except for restraining the tail, the body of animal is not bound or held in any way, so that the animal can freely access food and water based on its physiological needs.
The purpose for performing animal experiments is to observe physiological and pharmacological responses induced by drug administration (intravenously, subcutaneous, peritoneal, and muscular) or external stimulation (electric shock or pathogen) in the test animals, so as to estimate possible reaction that may occur to the human body under the same exposure. This further serves as a basic model for clinical experiments. Typically, animal experiments conducted to estimate physiological and pharmacological states are generally divided into two model types, the conscious model and the anesthetic model. In the conscious model, behavior and reaction are observed after a drug is administered to the animal via feeding, subcutaneous injection, peritoneal injection, and tail intravenous injection, or when the animal is stimulated by epidermal chip implant or electric shock and heat or cold. The benefit of this model is that the animal is in the conscious state when the experiment is carried out. Therefore, the physiological changes of the animal are purely the result of the experimental drug after drug administration or external stimulation, and the physiological parameters yielded reflect the true situation in vivo.
However, in the conscious model, a conventional animal experiment usually adopts a more invasive arterial catheter method that involves catheterization at a common carotid artery in the front neck of the experiment animal. Then, the catheter passes through the cortical layer and comes out from the back of the neck. The method also requires continuous infusion of an anticoagulant to avoid blood clotting in the catheter. Also, a large wound is produced when the experiment is conducted by the invasive arterial catheter method. For this reason, the experiment has to be suspended until the wound is healed. So, by this method, breeding time and cost are both increased, and the animal may become infected and die more easily. Moreover, the pain experienced during the wound healing also disturbs emotional state of the animal, further affecting accuracy of the experimental data.
Also, when the experiment is to measure the physiological and pharmacological reactions in the animal at a particular time point (such as 2 hours after drug administration), the conscious model often involves sampling the sacrificed animal somewhat before that time point due to the time taken for surgical catheterization. Consequently variable time errors may be produced due to inconsistent surgical skills, and physiological changes in the experiment animal during the surgical procedure may introduce further errors. Moreover, the same set of the experiments is often conducted continuously over several time points so that the experimental result is statistically significant. Therefore, a large number of animals are often sacrificed to complete each experiment, reducing the benefit gained from each sacrifice.
Accordingly, some researchers have proposed surgical methods and other alternatives. For example, a small hole is drilled through the skull into the brain of the experiment animal to insert a probe, such that the other end of the probe is coupled to a monitoring system. Other less invasive methods may also be adopted to improve the foregoing problems such as hooking up the animal with a miniature transmitter back rack. So, with the probe with built in signal transmitter implanted in the brain and messages transmitted from the radio, animal behavior is monitored and the influence of the experimental factor is observed. However, the brain surgery conducted on the live animal lengthens the overall time of the experimental procedure and increases the risk of surgical infection. And, in most of the research related to biochemistry, pharmacology or hemodynamics, many sets of experiments often need to be conducted under the same conditions according to the experimental design. Yet, it is not possible to conduct experiments on many sets of animals without limit at the same time due to the complicated process of brain surgery and high cost of the probe within the built in micro signal transmitter. For example, if a hemodynamics experiment is to be carried out, such as a blood pressure related experiment, one single experiment typically requires at least 24 sets of animals in order to provide statistically meaningful/significant results. Also, each animal is administered with the test drug and monitored one by one, different sets of animals have varying exposure duration. So, it is impossible to compare the data since the data yielded is not uniformly obtained.
Further, if the experiment animal is monitored by carrying the radio back rack, a experiment animal with great learning ability will gradually reject the stressful operation and bite or break free from the back rack, particularly as the experiment is repeated, making conducting the experiment more difficult. The restraining back rack carried by the experiment animal also leads to agitation and irritation of the animal, interfering with physiological test results. In addition, reception and transmission of radio signals may be easily blocked or interfered with by external environmental influences.
In another experimental approach, a photoelectric volume oscillometric method was developed in the medical field to measure the tail pressure of the experiment animal, so that less harm is done to the animal body while still fulfilling the requirements for a hemodynamic experiment. The photoelectric volume oscillometric method is a non-invasive method for measuring tail cuff pressure (TCP). As illustrated in FIG. 9, the experiment animal 1xe2x80x3 (such as rat) is confined in incubator 6xe2x80x3 with its tail fitted to the cuff 7xe2x80x3 for execution of the inflate/deflate cycle. In the inflation stage, the cuff 7xe2x80x3 records the oscillating wave of the vascular wall produced by blood flow pulsations. And, through the transformation of the oscillating wave, the heart rate (HR) and arterial pressure (AP) of the live animal are ascertained, thus monitoring the basic physiological state of the animal.
But as both the duration and number of times the experiment is repeated increase, a experiment animal with great learning ability begins to reject, resist, or even struggle with the idea of confinement in the incubator. As such, the test result may contain errors, such as exaggerated AP and unstable HR induced by the emotional stress. Thus, the result does not truly reflect the effect of the experimental factor on the animal body.
Therefore, it has become an urgent need in the biomedical field to develop an animal restraining apparatus and procedure for using the same, so as to minimize the harm done to the animal and to reduce costs while making operation much easier. Also, the apparatus should be designed in such a way as to allow the number of animal sets to be expanded as much as possible to fulfill the requirements of the hemodynamic experiment.
An objective of the present invention is to provide an animal restraining apparatus and restraining procedure for using the same, so that the physiological reaction of the live animal in the conscious state can be monitored continuously for more than 72 hours in the experimental condition.
Another objective of the present invention is to provide an animal restraining apparatus and restraining procedure for using the same, which allows increasing the number of the experimental sets without limit in order to satisfy the needs in the hemodynamic experiment, and to carry out all sets of the experiments in different conditions at the same time, yielding a larger sample number.
Another objective of the present invention is to provide an animal restraining apparatus and restraining procedure for using the same such that the apparatus and experiment may be operated more easily with lower costs to restrain the tail of the animal, while the animal is free to access food and move about in order to lessen the emotional stress of the animal.
Another objective of the present invention is to provide an animal restraining apparatus and restraining procedure for using the same, such that no invasive harm is done to the experiment animal, while avoiding agitation of the animal. And, as interference to the experiment caused by the emotional stress of the animal is minimized, the effects of the test drug are truly reflected in the monitoring result.
Another objective of the present invention is to provide the animal restraining apparatus and restraining procedure for using the same, which requires no administration of anesthetic or other drugs which could interfere with the experimental data, so that the monitoring result of the instrument is closer to the true physiological state in vivo.
Lastly, another objective of the present invention is to provide a animal restraining apparatus and restraining procedure for using the same, such that the drug is administered timely and quantitatively via the vein catheter, and the blood pressure and heart rate are continuously measured via the artery catheter, so as to sample the animal blood at any time point according to the experiment design. Thus, while conducting the experiment, neither blood sampling nor drug administration would cause discomfort to the animal.
As embodied and broadly described herein, the invention provides an animal restraining apparatus and restraining procedure for using the same applicable to research related to hemodynamic, pharmacology, or physiology testing, wherein the experiment animal is monitored in the conscious state without external interference. The restraining procedure using the animal restraining apparatus includes the following steps.
First, a live experiment animal (such as rat) is prepared. A catheter is inserted at the femoral artery and/or femoral vein of the live experiment animal, such that one end of the catheter makes contact with the body fluid of the experiment animal and the other end of the catheter is coupled to an external monitoring device.
Then, the live animal is restrained by a restraining apparatus, wherein the apparatus contains a food supply component to provide the experiment animal with food and water ad libitum, a plurality of partitioning boards to confine the animal in the restraining space, a supporting board to carry the experiment animal and the partitioning boards, and a fixing component fitted below the supporting board to restrain the experiment animal. On the partitioning board, an opening is formed near the fixing component, with a guiding component formed on the supporting board outside the opening. And, at least one hole is formed outside the guiding component on the supporting board. Accordingly, after the experiment animal is restrained in the restraining apparatus, the tail of the animal can pass through the opening in an partitioning board, the guiding component, and the hole of the supporting board, in order to allow contact with the fixing component. Then, the tail of the live experiment animal is fixed (by adhesive tape binding or other binding methods) on the fixing component, so as to restrain the animal from moving forwards, preventing accidental slippage of the catheter.
Besides fixing the tail with the adhesive tape, a heavy object may be hung from the tail of the experiment animal according to another embodiment of the animal experiment, to immobilize the lower body of the animal, preventing catheter slippage due to excessive movement of the animal during the experimental procedure.
According to the restraining apparatus of the present invention, the tail of the experiment animal is fixed below or above the cage to allow the most natural body posture of the experiment animal. As the tail-fixing step does not cause any pain or discomfort to the experiment animal, the agitation level of the experiment animal is reduced, and rejecting or resisting behavior typically associated with conventional apparatus is overcome. So, the above-mentioned animal experiment is not only beneficial to the operation of the experiment, but also keeps the experiment animal emotionally stable in the conscious state during the experiment, avoiding variation of the in vivo bioassay values, such as, unstable heart rate and increased tail cuff pressure, caused by excessive struggling or increased emotional stress. The drug is also administered timely and quantitatively via the vein catheter, while the blood pressure and heart rate are continuously measured via the artery catheter, so as to sample the animal blood at any time point according to the experimental design. As the level of interference caused by artificial factors is minimized, the experiment result is increasingly determined by the experimental factors, such that a more accurate experimental estimation value is yielded.
Also, since the restraining apparatus can be operated easily and has very low equipment cost, the number of the experiment sets can be expanded without limit as long as space permits. Many sets of animals can be experimented on under the same control conditions to provide a larger sample number. And, the drug inconsistency problem caused by administering the drugs to the animals one by one is eliminated.
With the restraining apparatus of the present invention, the experimenter only needs to open a small wound at the femoral artery or vein of the animal for catheterization. Since the wound recovers quickly with a low chance of infection, the experiment animal hardly experiences any pain. Furthermore, in comparison to traditional conscious state animal experiments, the experimental procedure of the invention can be combined with animal breeding. Moreover, the invention allows continuous monitoring for more than 72 hours (even more than 120 hours) in the conscious state without administering anesthetic and other drugs, allowing the experiment operator to accurately note the physiological changes in the experiment animal during that period of time. This continuous monitoring improves on the flaws in detecting animal condition associated with the traditional interval time point assay.